BEIRUT (Reuters) - Syria said on Wednesday it was investigating the source of a mortar bomb that killed five civilians in a residential border area in Turkey and urged restraint after Ankara responded by firing artillery shells at unspecified Syrian targets.
Syria's Information Minister Omran Zoabi also conveyed his condolences to the Turkish people, saying his country respected the sovereignty of neighboring countries. Other countries should also respect Syria's sovereignty and police their borders to stop gunmen from entering Syria, he said.
"The Turkish-Syrian border is long and is being exploited to smuggle weapons and terrorists who are committing massacres in Syria," Zoabi told Syrian state television.
"States and governments should act wisely, rationally and responsibly because there is a special situation (now) on the border with terrorist groups that are spread along it and pose a threat not only to Syria's national security but also to regional security."
NATO held an urgent meeting on Wednesday evening to discuss the exchange of fire, the most serious cross-border escalation since the revolt against Syrian President Bashar al-Assad erupted last year.
Syria says it is fighting Islamists groups and accuses Turkey and some Western and Arab countries of arming and funding rebels seeking to topple Assad.
(Reporting by Mariam Karouny and Marwan Makdissi in Damascus; Editing by Andrew Osborn)